I was looking around and saw Corsair TX V2 OEM Seasonic and Antec Earthwatt OEM Delta, only the Antec Earthwatt 750W is modular.
Is Corsair TX650 V2 the best choice or should I put more money and buy a TX750W V2 or Earthwatt 750W ?

Both Seasonic and Delta are good PSU manufacturers. I have a Delta 250W OEM unit from my Acer and it is still kicking strong. It depends on your budget whether you want to get the 650W or the 750W as I said before that both will work just fine for your PC. I would prefer a semi modular unit compared to a fully modular or a non modular PSU. Makes it a lot easier to remove cable clutter.

both are great choices, Corsair PSUs have THE best track record to date, especially the TX series price/reliability ratio is amazing! Although with the Antec you get modularity which you don't with the Corsair. I think a non-biased person would say they are equal value but I'm biased against Antec so I'd personally go with the Corsair!

But keep in mind the Antec is barely modular (only 3 modular cables...guess its better than none but we are far from a fully modular unit), not to mention its a 4 rail design vs the Corsair's single rail which IMO is superior. So I take what I said back, the Corsair is clearly superior with a better rail design/track record! Only 3 modular cables is not enough for me to change my mind regardless of brand...